unless I am mistaken...the one that I linked to that you can buy would wire inline before the upgrade harness...like this:
KEY ON (at night)>>> Sensor imediately turns headlight circuit on>>>headlight circuit energizes timer and it starts counting>>>TURN KEY TO START>>>kills power to timer>>>CAR STARTS>>>power is restored to headlight circuit, energizes timer>>>TIMER counts down to XX seconds...powers relay in upgrade harness>>>RELAY CLOSES>>>power from battery runs through relay and ignites ballasts.
Or at least thats my idea of how to wire it in. The other option is to wire it into the sensor circuit in the cabin...but I am not sure if that would require other modifications electrically or electronic wise to make the circuit work properly (BackInBlack) might know if a resistor or diode etc would need to be installed.
